The text below is taken from a rather splendid homily of Pope St. Leo the Great.
At Easter, beloved brethren, it was the Lord’s resurrection which was the cause of our joy; our present rejoicing is on account of his ascension into heaven. With all due solemnity we are commemorating that day on which our poor human nature was carried up, in Christ, above all the hosts of heaven, above all the ranks of angels, beyond the highest heavenly powers to the very throne of God the Father. It is upon this ordered structure of divine acts that we have been firmly established, so that the grace of God may show itself still more marvellous when, in spite of the withdrawal from men’s sight of everything that is rightly felt to command their reverence, faith does not fail, hope is not shaken, charity does not grow cold.
For such is the power of great minds, such is the light of truly believing souls, that they put unhesitating faith in what is not seen with the bodily eye; they fix their desires on what is beyond sight. Such fidelity could never be born in our hearts, nor could anyone be justified by faith, if our salvation lay only in what was visible.
And so our Redeemer’s visible presence has passed into the sacraments. Our faith is nobler and stronger because sight has been replaced by a doctrine whose authority is accepted by believing hearts, enlightened from on high. This faith was increased by the Lord’s ascension and strengthened by the gift of the Spirit; it would remain unshaken by fetters and imprisonment, exile and hunger, fire and ravening beasts, and the most refined tortures ever devised by brutal persecutors. Throughout the world women no less than men, tender girls as well as boys, have given their life’s blood in the struggle for this faith. It is a faith that has driven out devils, healed the sick and raised the dead.
Even the blessed apostles, though they had been strengthened by so many miracles and instructed by so much teaching, took fright at the cruel suffering of the Lord’s passion and could not accept his resurrection without hesitation. Yet they made such progress through his ascension that they now found joy in what had terrified them before. They were able to fix their minds on Christ’s divinity as he sat at the right hand of his Father, since what was presented to their bodily eyes no longer hindered them from turning all their attention to the realisation that he had not left his Father when he came down to earth, nor had he abandoned his disciples when he ascended into heaven.
The truth is that the Son of Man was revealed as Son of God in a more perfect and transcendent way once he had entered into his Father’s glory; he now began to be indescribably more present in his divinity to those from whom he was further removed in his humanity. A more mature faith enabled their minds to stretch upward to the Son in his equality with the Father; it no longer needed contact with Christ’s tangible body, in which as man he is inferior to the Father. For while his glorified body retained the same nature, the faith of those who believed in him was now summoned to heights where, as the Father’s equal, the only-begotten Son is reached not by physical handling but by spiritual discernment.